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1. Write the formula which shows the sequence of events that results in the production of a new protein molecule. Then explain what is happening in each step of the sequence.

2. Individuals who are carriers of genetic disorders are (A) homozygous (B) polygenic (C) heterozygous

Please help, you'll get 10 points!

2007-03-05 05:33:55 · 3 answers · asked by confidential 2 in Science & Mathematics Biology

I'm not cheating, I'm homeschooled. Its kinda hard to cheat when you're homeschooled.

2007-03-05 06:08:12 · update #1

3 answers

Protein Synthesis in two steps.
1.Transcription = DNA → RNA
2.Translation = RNA → protein

Proteins are assembled from amino acids using information encoded in genes. Each protein has its own unique amino acid sequence that is specified by the nucleotide sequence of the gene encoding this protein. The genetic code is a set of three-nucleotide sets called codons and each three-nucleotide combination stands for an amino acid, for example ATG stands for methionine. Because DNA contains four nucleotides, the total number of possible codons is 64; hence, there is some redundancy in the genetic code and some amino acids are specified by more than one codon. Genes encoded in DNA are first transcribed into pre-messenger RNA (mRNA) by proteins such as RNA polymerase. Most organisms then process the pre-mRNA (also known as a primary transcript) using various forms of post-transcriptional modification to form the mature mRNA, which is then used as a template for protein synthesis by the ribosome. In prokaryotes the mRNA may either be used as soon as it is produced, or be bound by a ribosome after having moved away from the nucleoid. In contrast, eukaryotes make mRNA in the cell nucleus and then translocate it across the nuclear membrane into the cytoplasm, where protein synthesis then takes place. The rate of protein synthesis is higher in prokaryotes than eukaryotes and can reach up to 20 amino acids per second.[5]

The process of synthesizing a protein from an mRNA template is known as translation. The mRNA is loaded onto the ribosome and is read three nucleotides at a time by matching each codon to its base pairing anticodon located on a transfer RNA molecule, which carries the amino acid corresponding to the codon it recognizes. The enzyme aminoacyl tRNA synthetase "charges" the tRNA molecules with the correct amino acids. The growing polypeptide is often termed the nascent chain. Proteins are always biosynthesized from N-terminus to C-terminus.


Homozygous
An organism is referred to as being homozygous at a specific locus when it carries two identical copies of the gene affecting a given trait on the two corresponding homologous chromosomes (e.g., the genotype is PP or pp when P and p refer to different possible alleles of the same gene). Such a cell or such an organism is called a homozygote.

A homozygous dominant genotype occurs when a particular locus has two copies of the dominant allele (e.g. PP). A homozygous recessive genotype occurs when a particular locus has two copies of the recessive allele (e.g. pp).

Pure-bred or true breeding organisms are homozygous. For example a homozygous individual could have the allele combinations PP or pp.


Heterozygous
An organism is a heterozygote or is heterozygous at a locus or gene when it has different alleles occupying the gene's position in each of the homologous chromosomes. In other words, it describes an individual that has 2 different alleles for a trait. In diploid organisms, the two different alleles were inherited from the organism's two parents. For example a heterozygous individual would have the allele combination Pp

Polygenic inheritance or quantitative inheritance:
refers to inheritance of a phenotypic characteristic (trait) that is attributable to two or more genes and their interaction with the environment. Unlike monogenic traits, polygenic traits do not follow patterns of Mendelian inheritance (qualitative traits). Instead, their phenotypes typically vary along a continuous gradient depicted by a bell curve.[1]

An example of a polygenic trait is human skin color. Many genes factor into determining a person's natural skin color, so modifying only one of those genes changes the color only slightly. Many disorders with genetic components are polygenic, including autism, cancer, diabetes and numerous others. In fact, most phenotypic characteristics are the result of the interaction of multiple genes.

2007-03-05 06:25:35 · answer #1 · answered by ANITHA 3 · 0 0

can you really do that? post your homework on here? I think #2 is B...

2007-03-05 05:42:35 · answer #2 · answered by Anonymous · 0 1

homework is for you to do so you can ACTUALLY learn something. Cheater!

2007-03-05 06:03:47 · answer #3 · answered by stickan8 3 · 0 1

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